Catheters designed for intravascular procedures such as angioplasty must have a number of characteristics. Such catheters must be able to transmit force along the length of the catheter shaft to allow it to be pushed through the patient""s vasculature. However, the catheter shaft must also retain sufficient flexibility to allow it to track over a guidewire through the often tortuous vasculature. Additionally, the catheter must be able to cross stenosed portions of the vascular anatomy. Prior art designs have supplemented polymer catheter shafts with a stiffening wire or mandrel.
There is a need for rapid exchange catheters having improved pushability, trackability and crossability providing enhanced performance characteristics. The present invention addresses this and other needs.
The invention is directed to a balloon catheter, preferably a rapid exchange type catheter, having a mandrel in an inflation lumen extending within the catheter shaft. The intravascular balloon catheters of this invention generally comprise an elongated catheter shaft having proximal and distal ends, an inflation lumen extending within the elongated catheter shaft to a location in the distal shaft section of the elongated shaft, and an inflatable balloon disposed on a distal portion of the distal shaft section having an interior in fluid communication with the inflation lumen. A distal port is in the distal end of the catheter shaft, and a proximal port is in the distal shaft section proximal to the inflatable balloon. A guidewire receiving lumen extends through a portion of the catheter shaft, between and in fluid communication with the distal and proximal ports.
A support mandrel is disposed within the inflation lumen and has a proximal end and a free distal end. The proximal end of the mandrel should be secured in a proximal section of the catheter shaft, and the mandrel distal end should extend distally of the proximal guidewire port, and is preferably free.
In one presently preferred embodiment, the guidewire lumen and the inflation lumen are substantially parallel to one another at the proximal guidewire port and become coaxial to one another distal of the proximal guidewire port. The free distal end of the support mandrel should extend in the inflation lumen to at least the area where the guidewire and inflation lumens become coaxial.
In another presently preferred embodiment, the catheter shaft further comprises a sleeve to secure a distal section of the support mandrel to a wall defining the inflation lumen. In this embodiment, the distal end of the mandrel preferably extends beyond the distal end of the sleeve and the sleeve is preferably disposed adjacent to the proximal guidewire port.
The catheter of the invention has improved pushability and crossability while maintaining more than adequate trackability due to the support mandrel in the inflation lumen with a free distal end located distal to the proximal guidewire port. A catheter with the support mandrel of the invention also has excellent resistance to catheter shaft kinking. Further, the design of this invention maximizes the cross sectional area of the inflation lumen along the length of the catheter while accommodating the support mandrel, to consequently improve inflation and deflation times. These and other advantages will become more apparent from the following detailed description and accompanying figures.